Tape cassette

ABSTRACT

An improved, Philips-type tape cassette having a shiftable tab for selectively blocking the opening formed by the removal of the conventional knock-out tab used to provide a means for determining the presence of pre-recorded material on the tape carried by the cassette. The two shells of the cassette have improved tongue and groove structure at the adjacent sides and ends to fit the shells together and to prevent relative movement therebetween. Relatively wide front and rear end walls on one of the shells provide a pair of beams of increased thickness to prevent bending of the cassette so as to maintain its structural integrity. An improved internal lock is provided near the central part of the rear wall where an attachment screw would be impractical. Each hub of the cassette has an improved leaderholding insert which is received within an outer peripheral recess and supports the tape across the recess to avoid &#39;&#39;&#39;&#39;spoking&#39;&#39;&#39;&#39; in the tape pack formed on the hub. Each of a pair of improved idler posts integral with one of the shells provides a pair of spaced, cylindrical bearing surfaces while providing a space for receiving lubricant. Tape guides near the open, tapeexposing extremity of the cassette are perpendicular to the inner surface of each shell to minimize the &#39;&#39;&#39;&#39;barber pole&#39;&#39;&#39;&#39; effect on the tape.

United States Patent 1 Biery et a1. 1

[ NOV. 12, 1974 4] TAPE CASSETTE [75] inventors: Pau1 J. Biery, SanJose; Vernon R. Schwartz, Cupertino; Roger N. J.

Tregear, San Jose, all of Calif.

[73] Assignee: Information Terminals Corp., Mountain View, Calif.

[22] Filed: July 31,1972

21 Appl. No.: 276,633

- [52] U.S. C1 360/132, 242/74, 242/199, 360/60 [51] Int. Cl. Gllb23/10, G1 lb 23/28 [58] Field of Search 274/4 C, 4 A, 11 C; 179/1002 Z,100.2 ZA; 242/199, 198, 200

[56] References Cited UNITED STATES PATENTS 3,416,150 12/1968 Lindberg,.lr 179/l00.2 Z 3,601,555 8/1971 Peterson 274/4 C X 3,617,067 11/1971Ban ..'179/100.2 Z 3,677,556 7/1972 Oosone I 179/1002 Z 3,686,470 8/1972Stahlberg et a1. 274/4 C X FOREIGN PATENTS OR APPLICATIONS 1,498,2889/1967 France 274/4 C Primary Examiner-George F. Mautz 57 ABSTRACT Animproved, Philips-type tape cassette having a shiftable tab forselectively blocking the opening formed by the removal of theconventional knock-out tab used to provide a means for determining thepresence of pro-recorded material on the tape carried by the cassette.The two shells of the cassette have improved tongue and groove structureat the adjacent sides and ends to fit the shells together and to preventrelative movement therebetween. Relatively wide from and rear end wallson one of the shells provide a pair of beams of increased thickness toprevent bending of the cassette so as to maintain its structuralintegrity. An improved internal lock is provided near the central partof the rear wall where an attachment screw would be impractical. Eachhub of the cassette has an improved leader-holding insert which isreceived within an outer peripheral recess and supports the tape acrossthe recess to avoid spoking in the tape pack formed on the hub. Each ofa pair of improved idler posts integral with one of the shells providesa pair of spaced, cylindrical bearing surfaces while providing a spacefor receiving lubricant. Tape guides near the open, tape-exposingextremity of the cassette are perpendicular to the inner surface of eachshell to minimize the barber pole effect on the tape.

7 Claims, 15 Drawing Figures PAIENTEL rem/121914 3.848.265

SHEEI 1; 0F 4 TAPE CASSETTE This invention relates to improvements inPhilipstype tape cassettes and, more particularly, to a tape cassettehaving improved mechanical stability.

In utilizing tape cassettes of the Philips-type for the precisionrecording and playback of information, such as digital or audioinformation, it is extremely important that the cassette be'mechanicallystable so that it will not warp with use or with age. Moreover, it mustnot change dimension or shape or otherwise undergo physical changes whensubjected to being roughly placed in or removed'from a tape transport.It must at all times be able to present the tape so that the latter willbe properly positioned with respect to a read-write head of the tapetransport. Conventional Philips cassettes generally are not stiff enoughand are not designed to meet the foregoing criteria. As a result, theconventional cassettes are not suitable for precision recording andplayback work especially when interchangeability between the transportand multiple playback of recorded information in the cassette areimportant.

The present invention is directed to a Philips-type tape cassette havinga number of improvements which cause the cassette to have a much greatermechanical stability than conventional Philips cassettes Thus, thecassette of this invention is especially suitable for precisionrecording and playback of digital, audio and other information, yet thecassette is simple in construction and can be produced in volume atminimum expense. Because of its improved construction, the cassette ofthis invention is more positively interchangeable with different tapetransports than is possible with conventional cassettes.

The cassette can also be made in a manner such that it can have a pairof shiftable tabs on the normally rear end wall for selectively openingor closing the holes initially closed by conventional knock-out tabsintegral with the cassette, the tabs being removed if the tape of thecassette is pre-recorded. However, it is oftentimes desirable to be ableto record on tape in a cassette whose knock-out tabs have previouslybeen removed. The shiftable tabs of the present invention are capable ofselectively. covering the holes formed by removal of the knock-out tabs,yet the tabs of the invention can be moved to standby positions whilestill being carried by the rear wall of the cassette; thus, they arenever separated from the cassette, once the latter is assembled.

An important improvement with respect to enhancing the mechanicalstability of the cassette is the use of'- tongue and groove structure attheopposed sides at one end of the cassette to provide a more positivefit between the two shells of the cassette yet prevent any relativemovement of the cassette shells after assembly. To this end, one of theshells has side and end ribs which are complementally receivable withincorresponding grooves in the sides and one end of the other shell. Theribs are capable of being snapped into the grooves inasmuch as thematerial of the shells can be somewhat resilient for this purpose, theresilience being sufficient to provide a releasable lock so as to keepthe shells in fixed positions relative to each other.

Another improvement relating to mechanical stability of the cassette isthe use of an additional releasable lock near the rear wall thereof in aregion where an attachment screw would be most impracticable because thetape pack prevents the inclusion of mounting structure for such a screw.Such lock includes a post on one of the shells with the post having alateral projection which snaps into a'recess near the rear wall of theother shell. Thus, the central part of the cassette near the rear wallis sufficiently locked together to prevent any tendency for the shellsto separate from each other or bend relative to each other in thisregion so as to maintain the structural integrity of the cassette.

A further improvement directed to improved mechanical stability is theprovision of front and rear end walls of increased width and thicknesson one of the shells to present apair of beams of increased strength toprevent side bending of the cassette and thereby distortion of the tapepath therethrough. Such beam thickness is twice that of conventionalPhillips-type tape cassettes and provides greatly increased stiffnessforthe cassette. As a result, this feature represents a vast improvementover conventional cassettes which are relatively flexible.

The tape cassette of this invention also has a pair of improved idlerposts which are integral'with one of the shells and are constructed toorient the idler pulleys.

thereon in a manner to assure that the tape will at all times move alonga predetermined path past the open, tape-exposing front face of thecassette. The posts also have a taper which allows them to be readilyremoved from a mold yet each post has two, cylindrical, spaced bearingsurfaces for the corresponding idler pulley so that is axis will besufficiently stable to cause the tape to follow the desired path. Inaddition, the configuration of the post defines a space within thepulley for receiving a lubricant, if desired, whereby the frictionbetween the post and pulley can be minimized.

Another improvement of the present invention relates to the hubs for thecassette wherein each hub has an improved leader locking means at itsouter periphery. The locking means includes an insert receivable withina recess in the outer periphery of the hub to hold the adjacent end of aleader to the hub. The outer surface of the insert is a substantialcontinuation of the outer periphery of the hub so that tape packdefects, such as spoking" will not occur as the tape pack builds up onthe hub.

The primary object of this invention isto provide a tape cassette of thePhilips-type having a number of improvements which greatly increase themechanical stability of the cassette so as to render the latterespecially suitable for use where precision recording and playback ofinformation is desired or necessary.

Another object of the present invention is to provide a Philips-typetape cassette having structural improvements which increase itsstiffness and render it more suitable for interchangeability whileassuring that the structural integrity of the cassette will bemaintained after long periods of use with different types of tapetransports.

A further object of this invention is to provide a Philips-type cassettehaving an. improved tab shiftably mounted thereon for movement into andout of blocking relationship to the hole formed by removal of theknock-out tab of the'cassette so that the hole can be selectively openedor closed after removal of the knockout tab.

Another object of this invention is to provide a. hub for a Philips-typecassette wherein the hub has an improved leader lock at its outerperiphery to positively hold the end of a leader coupled to the hub; thetape pack formed on the hub will not have defects in it, such as occurswith hubs having conventional leader locks.

Other objects of this invention will become apparent as the followingspecification progresses, reference being had to the accompanyingdrawings for an illustration of the invention.

In the drawings:

FIG. 1 is a perspective view of the tape cassette utilizing theimprovements of the present invention;

' FIG. 2 is a view similar-toFIG. l but showing the tape cassette fromadifferent angle and illustrating the shiftable tabs which are movableinto and out of closing realong line 7-7 of FIG. 1 FIG. 8 is a rear endelevational view of the other sidewall-of the cassette;

FIG. 9 is a plan view of the sidewall of FIG. 8, looking in thedirection of line 9-9.of FIG. 8;

FIG. 10 is a front-end elevational view ofthe sidewall of FIGS. 8 and 9;

FIG. 11 is an enlarged, cross-sectional view taken along line 1l-ll ofFIG. 9.

FIG. 12 is an end elevational viewof the improved hubs of the cassette,showing the hubs interconnected by a tape leader;

FIG. l3is an enlarged, fragmentarily, exploded view ofthe hub andimproved reel lock thereof together with a ram for inserting the reellock into an outer peripheral recess of the hub;

FIG. 14 is an enlarged, fragmentary, end elevational view of the hubwith the insert received within the recess thereof and before the end ofthe-leader has been sheared;-and

FIG. 15 is a view similar to FIG. 14 but showing the end of the leaderafter it has been sheared.

The tape cassette utilizing the improvements of the present invention isbroadly denoted by the numeral 10 and is a Phillips-type cassette. Ithas a pair of opposed shells l2 and 14 which mate to form a hollowhousing which receives a pair of tape hubs (not shown) on which aflexible, magnetic tape 16 is wound. A stretch 18 of the tape extendsalong the front, tape-exposing open extremity 20 of cassette l2 and isadapted to move past a read-write head as the tape is driven by acapstan, the head and capstan forming parts of a tape transport (notshown). Shells l2 and 14 are provided with openings 22 which expose theinner peripheries of the tape hubs therein and allow spindles on thetape transport to be removably coupled to the tape hubs.

' A first improvement for cassette 10 includes a pair of 3 tabs 24 and26 onthe rear wall 28 of the cassette 10 for movement into and out ofclosing relationship with respective openings or holes 30 in the rearwall 28. Openings 30 are of the type conventionally provided in aPhilips cassette when-the twoknock-out tabs thereof are removed. Suchknock-out tabs are formed in an integral fashion to one of the twoshells 12 and 14 and, when the knock-out tabs are across respectiveopenings 30, the tabs prevent a sensing pin from entering each opening,thus keeping a recording circuit of the tape transport in an enabledcondition. The tape of the cassette can, therefore, be recorded. Withthe knock-out tabs removed, the aforesaid sensing pin can enter eachopening 30, thereby disabling the recording circuit of the tapetransport so as to prevent recording on the tape. With the knock-outtabs removed, the user of the cassette will know that the tape ispre-recorded and that, without closing openings 30, it is not possibleto record new material thereon. Tabs 24 and 26 of cassette 10 allowopenings 30 to be selectively opened and closed, whereby the tape cannotbe recorded when openings 30 are open but can be recorded when suchopenings are closed.

Each of the tabs 24 and 26 is pivotally mounted on rear wall 28 formovementabout respective, parallel axes which are substantially normalto the major planes of shells 12 and 14. Each of thetabs includes agenerally rigid, flat, thin body 32 which is pivotally mounted on a base34 (FIG. 9), the latter having a bead 36 at the end remote from body 32.Preferably, body 32 and base 34 are of plastic material, are integralwith each other, and are interconnected at a line of weakness 38.

Base 34 of each of the tabs 24 and 26 is received within akeyhole-shaped slot formed by a pair of aligned slot sections or halvesin end webs integral with the respective shells l2 and 14 (FIG. 5).Shell 14 has webs 40 and 42 provided with a pair of keyhole-shaped slotsections 44 and 46, respectively. Webs 40 and 42 mate with respectivewebs 48 and 50 on the inner surface of shell 12. Webs 48 and 50 havekeyhole-shaped slot sections 52 and 54, respectively, when shells 12 and14 are coupled together, which mate to form the complete slots whichreceive respective bases 34 of the tabs. The width of each base 34 isessentially twice the depth of each of the two slot sections used toretain such base and the shape of the base, including bead'36 thereof,is complemental to each of the corresponding slots so that each base 34and its bead 36 can be removably mounted in the corresponding slot.

Webs 40 and 42 define, with the inner surface 56 (FIG. 5) of shell 14, apair of recesses 58 and 60 open to the rear edge 62 of shell 14.Similarly, webs 48 and 50 of shell 12 define recesses 64 and 66 whichare open to the rear edge 68 of shell 12. When the shells are mated,recesses 58 and 64 define one opening 30 and recesses 60 and 66 definethe second opening 30, it being clear that the rear openings of thekeyholeshaped slots are near the rear edges 62 and 68 of shells 12 and14, respectively.

Rear wall 28 (FIG. 2) is integral with shell 12 and projects laterallyfrom the inner surface 70 thereof (FIG. 9). Rear wall 28 has a pair ofshallow recesses 72 and 74 adjacent to the inner sides of recesses 64and 66, respectively. The depth of each of recesses 72 and 74 isapproximately equal to the thickness of body 32 of a respective tab.Moreover, the shape of each of recesses 72 and 74 is substantiallycomplemental to that of body 32 of each tab; thus, the outer, peripheraledge of the tab can be in frictional engagement with rear wall 28 at theouter, peripheral boundary of the corresponding recess 72 or 74 when thetab is in the recess,

i.e., when the tab is out of closing relationship to the adjacentopening 30. As shown in FIGS. 8 and 9, tab 26 has its body 32 out ofclosing relationship to recess 64 and spaced from recess 72. FIGS. 8 and9 also show tab 24 in its closed position, i.e., blocking the entranceof recess 66. A small recess extension 76 is provided for each of therecesses 72 and 74 to allow a pin or tool tobe inserted beneath a body32 in the corresponding recess to unseat the body and allow the tab tomove into a position blocking the adjacent opening.

Rear wall 28 has a pair of recesses 78 and 80 which partially surroundthe rear openings of respective recesses 64 and 66 and recesses 78 and80 mate with respective recesses 82 and 84 which partially surround therear openings of respective recesses 58 and 60, the depths of recesses78, 80, 82 and 84 being substantially equal with each other and equal tothe thickness of body 32 of each of the tabs 24 and 26. Thelastmentioned recesses also are complemental to outer peripheralportions of respective bodies 32 and the latter are adapted tofrictionally engage rear wall 28 when the corresponding tabs are inmated recesses 78, 84, 80 and 82, respectively. In this way, the tabscan be releasably held in place when they are in either their operativepositions closing openings 30 or in their standby positions out ofblocking relationship to respective openings 30.

Shell 14 has a pair of sides 86'and 88 which are provided withlongitudinal ribs 90 and 92, respectively. Ribs 90 and 92 are adapted tobe received within grooves 94 and 96, respectively, formed in the outerend faces of a pair of sides 98 and 100 integral with and forming partsof shell 12 (FIG. 9). Moreover, the outer end face of rear wall 28 has apair of grooves 102 and 104 which mate with and receive a pair of ribs106 and 108, respectively, formed on inner surface 56 of shell 14 whenthe two shells are coupled together as shown in FIGS. 1 and 2.

Shell 14 has webs 110 on its four corners, the webs projecting laterallyfrom inner surface 56. Each web 110 has a countersuck hole 112 thereinfor receiving a projection 114 on a corresponding corner of shell 12,the latter having webs 116 at its four corners, webs 116 being integralwith shell 12 and projecting laterally from inner surface 70 thereof.Insertion into hole 114A of self tapping assembly screws causes adiametral increase of cylindrical projection 114, thus allowing aninterference fit with complemental hole 112 as formed from correspondingwebs 110 so that holes 112 and projections 114 form tongue and groovestructures as do ribs 90, 92 106 and 108 and grooves 94, 96, 102 and104. When shells l2 and 14 are brought together, the various tonguesenter corresponding grooves and frictionally engage the adjacentstructure so that the shells are more positively held together and aremore preferably fitted together, inasmuch as the various tongues andgrooves prevent any tendency for one shell to move longitudinally of theother shell.

Another feature of the cassette is the lock provided by a rear post 118formed on the inner surface 56 of shell 14 (FIG. 7). Post 118 has arearwardly extending projection 120 which is adapted to be receivedwithin a recess 122 in a boss 124 which is integral with and extendsinwardly from rear wall 28 (FIGS. 9 and 11). Post 118 is sufficientlyresilient so as to yield to one side when the shells are moved together.As soon as projection 120 is aligned with recess 122, the projectionsnaps into the recess and the resilience of post 118 returns it to itsinitial position, thereby locking the shells together at that particularlocation.

Shell 14 is provided with a hole 126 for receiving a screw which isthreaded into an internallythreaded hole 128 in a boss 130 integral witha front partition 132 near the open front extremity 20 of the cassette.Also, projections 114 are internally threaded so that screws insertedinto holes 112 can be threaded into respective projections 114 to holdthe shells coupled to.- gether at the corners. A screw threaded intohole 128 in boss 130 holds the front central part of the cassettetogether, whereas, projection 120 of post 118, when received withinrecess 122, holds the rear central part of the cassette together. Thelock provided by post'118 is used because of the lack of structure nearthe rear central part of the cassette for mounting an attachment screw.1

Partition 132 substantially spans the distance between the innersurfaces of shells 12 and 14. Shell 12 is provided with a front recess134 which mates with a frontrecess 136 of shell 14. Partition 132 spansthe length of recess 134 and is intermediate the front and rearextremities thereof. The height of partition 132 is substantially equalto the distance between the inner surfaces of those portions of shells12 and 14 which define respective recesses 134 and 136. Shell 14 hasfour posts 138 at its front edge and the length of each post issubstantially equal to the height of partition 132 so that the outerends of posts 138 engage the inner surface portions 140 at the bottom ofrecess 134 on opposite sides of reinforcing webs 142 (FIG. 9).

Partition 132 has a pair of outer end webs 144 which are substantiallyhorizontally aligned with each other and a pair of inclined webs 146which span the distance between respective webs 144 and boss 130 (FIG.9).

A pair of outer tape guides 148 project forwardly from partition 132 atthe junction between respective webs 144 and 146. Similarly, a pair oftape guides 150 are integral with and project forwardly from respectivewebs 146 intermediate the ends of the latter. Guides 148 and 150 havefront, convex, tape-engaging surfaces which are generally perpendicularthe inner surface of shell 12. These convex surfaces are in generallyhorizontal alignment with each other and are aligned with entrancepassages 152 and 154 (FIG. 9) between front webs 156 and the adjacentside webs 158, webs 158 forming side extensions for partition 132.

Since rear wall 28 and partition 132 span the distance between theeffective inner surfaces of shells 12 and 14, such rear wall andpartition define beams whose widths are represented by the widths of therear wall 28 and partitions 132. The widths of these beams are muchgreater than the effective widths of front and rear end walls ofconventional Phillips-type tape cassettes so that such increased beamwidth serves to prevent side bending of the cassette to avoid distortingthe parts therein and to prevent errors due to mechanical misalignmentof the tape.

The perpendicular tape guides 148 and 150 allow tape 16 to move pastsuch guides without moving laterally thereof or being caused to barberpole. In conventional cassettes, tape guides similar to guides 148 and150 are slightly inclined to allow the cassettes to be removed frommolds used to-form the shells of the cassette.

Cassette 10 has a pair of idler pulleys 160 which are mounted onimproved idler posts 162 of the type shown in FIG. 3. Each post 162 isintegral with the inner surface of shell 12 near the front cornersthereof. Each post front includes a first cylindrical portion 164, abeveledportion 166 and a second cylindrical portion 168, beveled portion166 interconnecting portions 164 and 168 and cylindrical portion 168being of a smaller outer diameter than that of portion 164. Suchconstruction of the post permits it to be readily removed from a mold.Also, the outer surfaces of portions 164 and 168 define a pair of spacedbearing surfaces for the corresponding pulley 160 when the latter isprovided with a first bore 170 adjacent to a second bore 172 of smallerdiameter than bore 170. Moreover, when pulley 160 is mounted on post162, a wedge-shaped space 174 is formed between portion 166 and bore170. This space can be filled with a lubricant, if desired.

In use, the tape hubs, the tape and the idler pulley 160 are mounted inplace on shell 12. Slip sheets are also generally provided between theshells and hubs to minimize friction and the build-up of staticelectricity. The shells are then moved together and the tongue andgroove structures mentioned above provide a positive interconnection ofthe shells. The attachment screws are then put into place and theassembly of the cassette is complete. The cassette .is then ready foruse and is coupled to a tape transport to cause movement of the tapefrom one hub to the other past open extremity 20.

Tabs 24 and 26 can be operatively positioned as desired with respect toadjacent openings 30. The tabs are held in the corresponding recesses,whether in operative or standby positions, so that the tabs do notproject laterally from rear wall 28. The positions of the tabs can beselectively changed as desired or needed.

Construction of idler posts 162 is such as to give accurateperpendicularity with respect to shell 12. Thus, idler pulleys 160 onidler posts 162 will properly orient the tape relative to the openextremity of the cassette and thereby to a read-write head adjacent tosuch open extremity.

Cassette 10 is also provided with a pair of tape hubs 200 (FIGS. 12-15)having improved lead-locking means thereon. To this end, each hub 200has an outer peripheral recess extending between the end faces of thehub and including an inner, generally cylindrical recess portion 204 andan outer, generally funnelshaped portion 206 communicating with innerportion 204 and terminating at the cylindrical outer periphery 208 ofthehub. The inner and outer recess portions are formed by a pair of spacedprojections 205 and 207 forming parts of the hub and extending intorecess 202. The distance between projections 205 and 207 is less thanthe maximum transverse dimensions of inner and outer recess portions 204and 206. Inner portion 204 is defined by a cylindrical inner surface 209terminating at convex surfaces 210 and 212 which define the junctionsbetween inner and outer recess portions 204 and 206. Outer portion 206is defined by a pair of generally flat surfaces 213 which convergetoward each other as inner portion 204 is approached.

A plug or insert 214 having the same thickness as hub 200 is movableinto recess 202 to lock or hold a leader 216 therein in the manner shownin FIGS. 14 and 15, whereby the leader is coupled to the hub. Insert 214has a first, generally cylindrical body 218 substantially complementalto inner recess portion 204 and a second, transversely funnel-shapedbody 220 substantiallycomplemental to an outer recess portion 206,bodies 218 and 220 being integral with each other. The cylindrical,outer surface 222 of body 218 merges smoothly with the opposed,convergent sides 224 of body 220 (FIG. 13) to present concave surfaces226 and 228 which are complemental to surfaces 210 and 212,respectively. The outer peripheral surface 230 of body 220 is arcuateand, when insert 214 is in its operative position (FIGS. 14 and 15),forms a substantial continuation of cylindrical outer periphery 208- ofhub 200. To this end, surface 230 has a radius of curvaturesubstantially the same as that of outer periphery 208.

Insert 214 is formed of a material which generally does not yield but iscapable of being sheared. It has been found that Delrin is a materialsuitable for'this use.

Insert 214 is adapted to be forced by a ram 232 into its operativeposition in recess 202. As the insert is moved into the recess, itforces one end margin of leader 216 into the recess. The leader thusextends along the firmly clamps between the surfaces defining recess 202and the outer surfaces of insert 214. This operation is preferablyperformed by the use of a jig wherein the end margin of the leader isplaced near the entrance to recess 212, then insert 214 is placedbetween the leader and the ram. When the ram is actuated, it forces theinsert to move toward and into recess 202 and, in turn, forces theleader into the recess ahead of the insert. Since the insert issubstantially complemental to recess 202, the portions of the hubdefining surfaces 210 and 212 yield to allow body 218 of insert 214 toenter inner recess portion 204. Hub 200 is formed of a suitableyieldable material to provide for this action.

Ram 232 is provided with a transversely V-shaped knife portion 234 whichis used to shear end portion 238 of leader 216 from the rest of theleader. After the insert is in its operative position and as ram 232continues forwardly through a small distance, end portion 238 is cleanlycut, the knife portion leaving body 220 intact. Thus, when the ramcompletes its forward stroke, the end of the leader spaced inwardly ofouter periphery 208 (FIG. 15) and outer peripheral surface 230 of body220 will be substantially circumferentially aligned with outer periphery208 so as to form a substantial continuation of the latter. Notches 238and 240 (FIG. 15) at the ends of surface 230 do not impair theeffectiveness of surface 230 sufficiently to cause spoking or other tapepack defects; thus, the tape can be wound onto the hub 200 and beadequately supported by surface 230 so as to avoid such defects.

The improved leader lock and the way in which it is coupled to hub 200provides a quick way to attach a leader to the hub. The resultingattachment eliminates the build-up of tape markings, such as spoking orthe like, by supporting the tape properly across the span of recess 202.Also, the geometry of insert 214 assures that the leader will bepositively locked at all times. For instance, if there is a force on theleader'in the direction of arrow 242 (FIG. 15), the insert 214 will tendto pivot in a counterclockwise sense about junction 212.

However, this causes body 218 to press against leader 216 in thevicinity of surface 210, thereby effectively locking the leader againstmovement out of recess 202. In this way, the leader can be preventedfrom slipping away from the hub even though extremely large longitudinalforces are applied to the leader tending to pull it out of the recess.

We claim:

1. In a tape cassette: a housing having a wall provided with a holetherethrough for receiving a sensor pin; a tab for blocking said hole toprevent the insertion of the sensor pin therein; means mounting the tabon the shell for rotation from a first position out of closingrelationship to the hole to a second position in closing relationship tosaid hole, whereby the latter can be selectively blocked; and meansengageable with the outer peripheral edge of said tab for releasablyholding the same in either of said positions.

2. In a tape cassette: a housing having a front wall and a rear wall andadapted to receive a pair of tape reels therein and to allow the tape onthe reels to move adjacent to and along the front wall thereof, the rearwall having a pair of spaced openings therein and a recess for eachopening, respectively, each recess substantially surrounding thecorresponding opening and extending laterally therefrom; a tab for eachopening, respectively; and means coupled with each tab, respectively,for pivotally mounting the same on said housing for movement from afirst position blocking the corresponding opening to a second positionspaced from the opening and disposed within the laterally extendingportion of the corresponding recess, said housing having edge portionsnear said rear wall for frictionally engaging the corresponding tab toreleasably hold the latter against movement when'the tab is in either ofsaid positions.

3. In a tape cassette as set forth in claim 2, wherein each tab includesa bead at one end and is provided with a transverse line of weaknessspaced from the bead, said line of weakness defining the hinge line forthe tab, the housing having a keyhole-shaped slot for receiving the beadand the adjacent portion of each tab, respectively, with the slotextending to the corresponding recess and the hinge line being disposedat the outer end of the slot.

4. In a tape cassette as set forth in claim 2, wherein each recess has apair of adjacent side-by-side sections corresponding to the first andsecond positions, respectively, of a tab, each tab having a flat bodyadapted to be complementally received within the corresponding recesssection, the depth of each recess section being substantially the sameas the thickness of the corresponding tab body.

5. In a tape cassette: a housing having a wall provided with a holetherethrough for receiving a sensor pin; a tab including a body having apair of opposed ends and adapted for blocking said hole to prevent theinsertion of the sensor pin therein; and a base hingedly secured to oneend of said body, said base having a mounting bead at its outer end,there being a transverse hinge line between said base and said body,said housing having a boss adjacent to said wall, said boss having arecess for receiving the bead with the recess being spaced inwardly fromthe outer surface of the wall, the hinge line being adjacent to saidouter surface of the wall to permit said body to pivot about the hingeline when the bead is received in the recess whereby the tab is mountedon the shell for movement into and out of closing relationship to thehole to permit the latter to be selectively blocked.

6. In a tape cassette: a housing having a wall provided with a holetherethrough for receiving a sensor pin; and a tab for blocking saidhole to prevent the insertion of the sensor pin therein, the tab havinga transverse hinge line intermediate its ends and being provided with abead at one end thereof, said housing having a boss provided with akeyholeshaped slot therein for receiving the bead and the adjacentportion of the tab, the slot having a length substantially equal to thedistance between the bead and the hinge line of the tab, whereby the tabcan be mounted on the shell for movement into and out of closingrelationship to the hole to permit the latter to be selectively blocked.

7. In a tape cassette: a housing having a wall provided with a holetherethrough for receiving a sensor pin; a tab for blocking said hole toprevent the insertion of the sensor pin therein, the tab being pivotallymounted on the housing near the wall for movement into and out ofclosing relationship to the hole, whereby the latter can be selectivelyblocked, said wall having a recess formed therein with the recess havinga pair of side-by-side sections, each of the sections being generallycomplemental to a portion of said tab, one of the sections being inrecess sections.

1. In a tape cassette: a housing having a wall provided with a hole therethrough for receiving a sensor pin; a tab for blocking said hole to prevent the insertion of the sensor pin therein; means mounting the tab on the shell for rotation from a first position out of closing relationship to the hole to a second position in closing relationship to said hole, whereby the latter can be selectively blocked; and means engageable with the outer peripheral edge of said tab for releasably holding the same in either of said positions.
 2. In a tape cassette: a housing having a front wall and a rear wall and adapted to receive a pair of tape reels therein and to allow the tape on the reels to move adjacent to and along the front wall thereof, the rear wall having a pair of spaced openings therein and a recess for each opening, respectively, each recess substantially surrounding the corresponding opening and extending laterally therefrom; a tab for each opening, respectively; and means coupled with each tab, respectively, for pivotally mounting the same on said housing for movement from a first position blocking the corresponding opening to a second position spaced from the opening and disposed within the laterally extending portion of the corresponding recess, said housing having edge portions near said rear wall for frictionally engaging the corresponding tab to releasably hold the latter against movement when the tab is in either of said positions.
 3. In a tape cassette as set forth in claim 2, wherein each tab includes a bead at one end and is provided with a transverse line of weakness spaced from the bead, said line of weakness defining the hinge line for the tab, the housing having a keyhole-shaped slot for receiving the bead and the adjacent portion of each tab, respectively, with the slot extending to the corresponding recess and the hinge line being disposed at the outer end of the slot.
 4. In a tape cassette as set forth in claim 2, wherein each recess has a pair of adjacent side-by-side sections Corresponding to the first and second positions, respectively, of a tab, each tab having a flat body adapted to be complementally received within the corresponding recess section, the depth of each recess section being substantially the same as the thickness of the corresponding tab body.
 5. In a tape cassette: a housing having a wall provided with a hole therethrough for receiving a sensor pin; a tab including a body having a pair of opposed ends and adapted for blocking said hole to prevent the insertion of the sensor pin therein; and a base hingedly secured to one end of said body, said base having a mounting bead at its outer end, there being a transverse hinge line between said base and said body, said housing having a boss adjacent to said wall, said boss having a recess for receiving the bead with the recess being spaced inwardly from the outer surface of the wall, the hinge line being adjacent to said outer surface of the wall to permit said body to pivot about the hinge line when the bead is received in the recess whereby the tab is mounted on the shell for movement into and out of closing relationship to the hole to permit the latter to be selectively blocked.
 6. In a tape cassette: a housing having a wall provided with a hole therethrough for receiving a sensor pin; and a tab for blocking said hole to prevent the insertion of the sensor pin therein, the tab having a transverse hinge line intermediate its ends and being provided with a bead at one end thereof, said housing having a boss provided with a keyhole-shaped slot therein for receiving the bead and the adjacent portion of the tab, the slot having a length substantially equal to the distance between the bead and the hinge line of the tab, whereby the tab can be mounted on the shell for movement into and out of closing relationship to the hole to permit the latter to be selectively blocked.
 7. In a tape cassette: a housing having a wall provided with a hole therethrough for receiving a sensor pin; a tab for blocking said hole to prevent the insertion of the sensor pin therein, the tab being pivotally mounted on the housing near the wall for movement into and out of closing relationship to the hole, whereby the latter can be selectively blocked, said wall having a recess formed therein with the recess having a pair of side-by-side sections, each of the sections being generally complemental to a portion of said tab, one of the sections being in substantially surrounding relationship to said opening, the outer peripheral edge of the tab being movable into releasably holding relationship to the portions of the wall defining the recess when the tab is in either of said recess sections. 